End cap locking means for hydraulic cylinders and method

ABSTRACT

A hydraulic cylinder comprises a housing having an end cap threadably mounted on an end thereof. A cylindrical gland is closely fitted within the housing and end cap to transmit a locking force from a set screw, threadably mounted on the end cap, to diametrically opposed portions of the interengaging threads attaching the housing and end cap together.

United States Patent 1191 Goade END CAP LOCKING MEANS FOR HYDRAULICCYLINDERS AND METHOD [75] inventor: James C. Goade, Joliet, Ill.

[73] Assignee: Caterpillar Tractor Co., Peoria, 111.

[22] Filed: Apr. 7, 1972 [21] Appl. No.: 242,101

[52] U.S. Cl. 92/168, 92/171 [51] Int. Cl. F16] 15/18, Fl6j 11/04 [58]Field of Search 92/169, 170, 171, 92/165, 166,167,168

[56] References Cited UNITED STATES PATENTS 2,891,513 6/1959 Fagge92/166 [4 Dec. 11, 1973 3,138,073 6/1964 Whitehouse 92/169 3,334,7738/1967 Bimba 92/165 R 3,559,540 2/1971 Sheldon 92/168 Primary Examiner-Paul E. Maslousky Attorney-Paul S. Lempio et al.

[57] ABSTRACT A hydraulic cylinder comprises a housing having an end capthreadably mounted on an end thereof. A cylindrical gland is closelyfitted within the housing and end cap to transmit a locking force from aset screw, threadably mounted on the end cap, to diametrically opposedportions of the interengagingthreads attaching the housing and end captogether.

8 Claims, 2 Drawing Figures END CAP LOCKING MEANS FOR HYDRAULICCYLINDERS AND METHOD BACKGROUND OF THE INVENTION This invention relatesto locking means for locking threadably attached members in afixed,axial position relative to each other. The locking means is particularlyadapted for locking of an end cap on the housing of a hydrauliccylinder.

A recurring problem with respect to the assembly and disassembly of ahydraulic cylinder is one of providing reusable locking means fornormally locking its end cap in position during cylinder operation andfor permitting the end cap to be removed expeditiously for servicingpurposes. One type of conventional locking means utilizes a pronouncedinterference fit between interengaged thread portions of the end cap andhousing. For example, such interference fit may be achieved by suitablymachining or deforming limited areas of the thread portions.

A common disadvantage thereof resides in the inability of such lockingmeans to continuously resist axial displacement 'of the interengagingthread portions, resulting in the loosening of the end cap. The lockingmeans also inhibits the expeditious attachment of the end cap on thehousing and requires the application of a substantially high torquingforce, by a wrench or the like, substantially throughout the entireaxial length of the interengaging threads. Considerable time is thusrequired for assembly purposes, in contrast to the assem- .bly ofmembers having standard threads formed thereon which can beexpeditiously interengaged by hand.

Set screws, threadably mounted in such end caps, have also been widelyused to achieve such locking functionby directly engaging underlyingthread portions of a respective housing. In addition to deforming suchthread portions, uncoupling of the members prior to disengagement of theset screw oftentimes results in the deformation and possible strippingof the threads formed on the housing.

SUMMARY AND OBJECTS OF THE INVENTION interenga'ging threads which arediametrically opposed tosuch locking means, via an intermedaite forcetransmitting means.

Another object of this invention is to employ such locking means todetachably secure an end cap on the housing of a hydraulic cylinder.

Other objects and advantages of this invention will become apparent uponreference to .the following description and accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side elevational view ofthe rod end of a double-acting hydraulic cylinder, embodying the presentinvention; and

2 FIG. 2 is an enlarged, partially, sectioned view, taken in thedirection of arrows II-II in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, adouble-acting hydraulic cylinder 10, disposed on a longitudinal axis Xthereof,

comprises an end cap 11 threadably mounted by interengaging,circumferential thread means 12 on the end of a cylindrical housing 13.The cylinder further comprises a rod 14 and attached piston 15,reciprocally mounted in the housing, and an annular sealing gland orforce transmitting means 16 mounted on the rod within the housing andcap. Although force transmitting means 16 and a cooperating threadlocking means 17 of this invention are herein described in associationwith a double-acting hydraulic cylinder, it should be understood thatsuch means are adapted for use in other applications requiring thepositive securance of two threaded members together.

The end cap comprises an annular portion 18 having a contiguous endflange 19 positioned thereon to abut gland 16 and to extend radiallyinwardly towards axis X. The flange defines a circular aperture 20therethrough to accommodate reciprocation of rod 14. A recessed,circumferentially extending surface 21 is formed internally on the cap,between thread means 12 and flange 19.

The locking means comprises a radially disposed threaded hole 22, formedthrough the sidewall of the end cap to intersect surface 21. A setscrew23 is threadably mounted in the hole and terminates at a cup point 24,formed on its lower end. The cup point normally engages an outer,circumferentially disposed surface 25 of a radially outwardly extendingflange 26, formed on gland 16 to be concentric with respect to surface21.

The gland further comprises a radially disposed surface 27 which abutsan end of housing 13 and a cylindrical portion 28 telescopically mountedin close fitting relationship within the housing. The rod isreciprocally mounted in an annular collar bearing 29 and axially spacedannular lip seals 30, each suitably mounted within a groove formedinternally on the gland. The rod may be connected to any suitable workimplement for actuating same upon selective extension or retractionoftherod. w i

Hydraulic fluid may be alternately introduced into and exhausted fromclosed chambers defined on either side of the piston by suitable lines,one of which is shown at 31, .in a conventional manner. A spanner wrenchor the like (not shown) may be used to engage an aperture 32, formedthrough annular portion 18 of the end cap, to tighten or loosen the capon the housing. Alternatively, a standard chain wrench (not shown),preferably having a torque indicator associated therewith, can besuitably mounted on the cap .to rotate same.

Once the end cap is threadably mounted on the housing under a torque of350 ft. lb., for example, ocking means 17 is actuated to preventinadvertent removal of the end cap. The locking function is accomplishedby engaging a hexagonal socket 33,0f setscrew 23 with an allen ,wrench(notshown) to move the setscrew radially inwardly until cup point 24thereof frictionallyvengages surface 25 of gland l6.

Further tightening of the setscrew will apply a radial load to the glandwhich functions as a force transmitting means to create a substantialinterference fit at thread portions 34 of thread means 12 which arediametrically opposed to the location of the setscrew. Such interferencefit will resist turning of the end cap relative to housing to preventinadvertent loosening and disengagement thereof. In addition, should aserviceman fail to loosen setscrew 35 prior to his attempting to removethe end cap, threads 12 will not be damaged.

In view of the foregoing, it is readily apparent that this inventionprovides an economical and reusable locking means and method forthreadably attached members which facilitates expeditious assembly anddisassembly and continuously provides reliable retention of the threadedmembers together. While the invention has been described and shown withparticular reference to the preferred embodiment, it is apparent thatvariations are possible that would fall within the scope of the presentinvention which is not intended to be limited except as defined in thefollowing claims. For example, first threaded member 11 could comprise astandard nut suitably attached to second threaded member 13, such as ashank, and to force transmitting member 16 to form an attachment adaptedfor use in a wide variety of applications.

What is claimed is:

1. A hydraulic cylinder disposed on a longitudinal axis thereofcomprising a housing,

an end cap,

circumferential thread means threadably mounting said end cap on an endof said housing,

locking means operativelyy connected to said cylinder for indirectlyapplying a force to thread portions of said thread means to create asubstantial interference fit thereat and force transmitting means,comprising a tubular member positioned between said locking means andsaid thread portions, for transmitting said force from said lockingmeans to said thread portions, said thread portions being diametricallyopposed to said locking means and said locking means being disposed onsaid cylinder to apply said force radially inwardly towards said axisand through said tubular member to said thread portions.

2. The invention of claim 1 wherein said hydraulic cylinder furthercomprises a piston and an attached rod reciprocally mounted in saidhousing, said rod extending through said end cap, and wherein saidtubular member comprises a gland mounted within said housing and saidend cap and having said rod reciprocally mounted therein.

3. The invention of claim 2 wherein said gland comprises a radial flangecomprising a radially disposed surface abutting an end of said housingand a circumferentially disposed surface engaged by said locking means,said end cap having a radially disposed flange formed thereon abuttingan end of said gland.

4. The invention of claim 1 wherein said locking means comprises a setscrew threadably attached to said end cap.

5. A first member,

a second member,

circumferential thread means threadably mounting said first member onsaid second member to dispose them on a common, longitudinal axis,

locking means connected to said first member for applying a forcethereat, and

force transmitting means comprising a tubular member positioned betweensaid first and second members for transmitting the force applied by saidlocking means to thread portions of said thread means to create asubstantial interference fit thereat,.said thread portions beingdiametrically opposed to said locking means and said locking means beingdisposed on said first member to apply said force radially inwardlytowards said axis and through said tubular member to said threadportions.

6. A threaded assembly comprising:

a pair of threaded member, individually including threaded portionsinterconnectible in screw threaded relation and having a circumferentialsurface separate from their respective threaded portions;

a tubular force transmitting member having a first portiontelescopically disposed with respect to said circumferential surface ofone of said threaded members and having a second portion telescopicallydisposed with respect to said circumferential surface of the other ofsaid threaded members; and

lock means, comprising a set screw threadably supported in one of saidthreaded members and threadably adjustable into and out of frictionalengagement with said force transmitting member, in radial forcetransmitting relationship between the said one of said threaded membersand said first portion of said force transmitting member to urge saidsecond portion thereof into frictional engagement with saidcircumferential surface of said other of said threaded members at apoint substantially diametrically opposite to said lock means to preventunintentional relative rotation between said threaded members.

7. The threaded assembly of claim 6 wherein the pair of threaded membersconstitute the cylinder and end cap of a hydraulic jack.

8. The threaded assembly of claim 7 wherein the force transmittingmember constitutes a bearing and seal gland, mounted in said cylinder,and including an annular flange disposed in locked position between anend of said cylinder and said end cap.

1. A hydraulic cylinder disposed on a longitudinal axis thereofcomprising a housing, an end cap, circumferential thread meansthreadably mounting said end cap on an end of said housing, lockingmeans operativelyy connected to said cylinder for indirectly applying aforce to thread portions of said thread means to create a substantialinterference fit thereat and force transmitting means, comprising atubular member positioned between said locking means and said threadportions, for transmitting said force from said locking means to saidthread portions, said thread portions being diametrically opposed tosaid locking means and said locking means being disposed on saidcylinder to apply said force radially inwardly towards said axis andthrough said tubular member to said thread portions.
 2. The invention ofclaim 1 wherein said hydraulic cylinder further comprises a piston andan attached rod reciprocally mounted in said housing, said rod extendingthrough said end cap, and wherein said tubular member comprises a glandmounted within said housing and said end cap and having said rodreciprocally mounted therein.
 3. The invention of claim 2 wherein saidgland comprises a radial flange comprising a radially disposed surfaceabutting an end of said housing and a circumferentially disposed surfaceengaged by said locking means, said end cap having a radially disposedflange formed thereon abutting an end of said gland.
 4. The invention ofclaim 1 wherein said locking means comprises a set screw threadablyattached to said end cap.
 5. A first member, a second member,circumferential thread means threadably mounting said first member onsaid second member to dispose them on a common, longitudinal axis,locking means connected to said first member for applying a forcethereat, and force transmitting means comprising a tubular memberpositioned between said first and second members for transmitting theforce applied by said locking means to thread portions of said threadmeans to create a substantial interference fit thereat, said threadportions being diametrically opposed to said locking means and saidlocking means being disposed on said first member to apply said forceradially inwardly towards said axis and through said tubular member tosaid thread portions.
 6. A threaded assembly comprising: a pair ofthreaded member, individually including threaded portionsinterconnectible in screw threaded relation and having a circumferentialsurface separate from their respective threaded portions; a tubularforce transmitting member having a first portion telescopically disposedwith respect to said circumferential surface of one of said threadedmembers and having a second portion telescopically disposed with respectto said circumferential surface of the other of said threaded members;and lock means, comprising a set screw threadably supported in one ofsaid threaded members and threadably adjustable into and out offrictional engagement with said force transmitting member, in radialforce transmitting relationship between the said one of said threadedmembers and said first portion of said force transmitting member to urgesaid second portion thereof into frictional engagement with saidcircumferential surface of said other of said threaded members at apoint substantially diametrically opposite to said lock means to preventunintentional relative rotation between said threaded members.
 7. Thethreaded assembly of claim 6 wherein the pair of threaded membersconstitute the cylinder and end cap of a hydraulic jack.
 8. The threadedassembly of claim 7 wherein the force transmitting member constitutes abearing and seal gland, mounted in said cylinder, and including anannular flange disposed in locked position between an end of saidcylinder and said end cap.